Chapter 1: Introduction to Chemistry

What is chemistry?OThe study of the composition of matter and the changes it undergoes.

OWhat is matter?OAnything that has mass and occupies space.

What’s the Difference Between Mass and Weight?

Mass WeightO Measure of the

amount of matter in an object.

O Needs a balance.

O A force that measures the pull of gravity on an object.

O Needs a scale.

Five Areas of Chemistry

O Organic Chemistry: chemicals containing carbon

O Inorganic Chemistry: chemicals NOT containing carbon

O Biochemistry: processes in organismsO Analytical Chemistry: composition of

matterO Physical Chemistry: mechanism, rate, and

energy transfers in matter during changes

Which area of study matches each of the following?

ODeveloping processes for efficient steel production

OStudying how lack of calcium affects bone growth

OMeasuring amount of lead in drinking water

OResearching differences between C2H5OH and CH3OH

OComparing energy differences needed to walk up or run up steps

Two Types of Chemical Research

Pure ChemistryApplied

ChemistryO Pursuit of

chemical knowledge for its own sake

O “I’ll experiment and see what I discover.”

O Research for a practical goal or application.

O “I’m looking for a cure for cancer.”

Why Study Chemistry?O Explains the natural worldO Energy, medicine, materials,

biotechnology, agriculture, environment, universe

O Helps prepare for a careerO Many different jobs using

chemistryO Helps create informed citizens

Antoine Lavoisier

O “Father of Modern Chemistry”O Changed chemistry from

observations to measurementsO Determined that oxygen is needed to

burnO Found and named elementsO Wrote textbooksO Law of Conservation of MatterO Made very precise balance, great labO Collaborated scientifically with peers

Scientific Method

OLogical, systematic approach to a scientific problem

OObservation: using senses to get information

OHypothesis: proposed explanation for an observation

OExperiment: procedure to test a hypothesis

Variables in an ExperimentManipulated

(Independent) Variable

Responding (Dependent) Variable

O What the experimenter changes

O Often time or temperature

O Plotted on x-axis

O The variable observed in an experiment

O Plotted on y-axis

What’s the Difference Between a Theory and a Law?

Scientific Theory Scientific Law

O Well-tested explanation for a broad set of observations

O Cannot be provedO Theory of Relativity,

Big Bang Theory

O Concise statement summarizing results of many experiments and observations

O Laws of Gravity, Law of Conservation of Matter

Experiments

TheoryHypothesis

Scientific Law

Observations

May be revised May be modified

Summarizes the results of many observations and experiments

Graphing in Chemistry

OGraphs display data in a concise form.

OGraphs predict trends in data.OGraphs allow extrapolation to points

beyond data limits.OLine graphs very common.OFive major parts: title, independent

variable, dependent variable, scales for each axis, legend (if needed)

Graph TitleO ALWAYS y-axis name vs. x-axis

name!O DO NOT use abbreviations in title

except for vs.

Velocity vs. Time

Independent (Manipulated) Variable

OControlled by experimenterOIncludes time, depth,

temperatureOPlaced on x-axis (horizontal

axis)

Dependent (Responding) Variable

ODirectly affected by the independent variable

OChanges in response to changes in independent variable

OPlaced on y-axis

Scales for Each Axis

O Must include all data points.O Scale for each axis is dictated by

data values.O Axis scales are independent of each

other (both do not have to start on same number).

O Scales DO NOT have to start at zero!O Scale MUST be consistent on the axis

(same interval throughout).O DO NOT USE A BREAK ON THE SCALE!

Example of Scales

Breaks on Axis

DO NOT USE A BREAK ON YOUR GRAPH!

Axes Titles and UnitsO Each axis needs a title and a unit.O Do not abbreviate titles.O Put the unit in parenthesis after the

title.Voltage vs. FrequencyVoltage vs.

Frequency

Legend

OOnly used when needed for clarity.

OShort and concise.

Line of Best Fit GraphsOFrequently used in chemistry.OIf data points do not form a

straight line, line is drawn as an average through the points.

ODraw one thin line using a ruler.

Extrapolation O To infer or estimate by extending or

projecting from known information.O Can get information on points not

tested in lab.O Make dotted line with a ruler to

extend graph.